U.S. patent application number 11/117931 was filed with the patent office on 2006-11-02 for satellite radio based vehicle positioning system.
Invention is credited to Brian W. Fillwock, Anthony Gerard Lobaza.
Application Number | 20060247856 11/117931 |
Document ID | / |
Family ID | 37195054 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060247856 |
Kind Code |
A1 |
Lobaza; Anthony Gerard ; et
al. |
November 2, 2006 |
Satellite radio based vehicle positioning system
Abstract
A vehicle positioning system architecture according to the
invention employs a satellite radio system ("SRS") to deliver
global positioning system ("GPS") correction data to vehicles. A
vehicle having a compatible onboard positioning system receives
standard GPS data from GPS satellites, along with SRS signals from
SRS satellites and/or SRS terrestrial repeaters. The onboard
vehicle positioning system corrects the GPS data with GPS
correction data received via the SRS signals.
Inventors: |
Lobaza; Anthony Gerard;
(Bloomfield Hills, MI) ; Fillwock; Brian W.;
(Chesterfield Township, MI) |
Correspondence
Address: |
GENERAL MOTORS CORPORATION;LEGAL STAFF
MAIL CODE 482-C23-B21
P O BOX 300
DETROIT
MI
48265-3000
US
|
Family ID: |
37195054 |
Appl. No.: |
11/117931 |
Filed: |
April 29, 2005 |
Current U.S.
Class: |
701/469 |
Current CPC
Class: |
G01S 19/072 20190801;
G01C 21/28 20130101 |
Class at
Publication: |
701/213 ;
701/216 |
International
Class: |
G01C 21/00 20060101
G01C021/00 |
Claims
1. A method for determining the position of a vehicle, said method
comprising: receiving, via an onboard vehicle subsystem, global
positioning system ("GPS") signals originating from GPS satellites,
said GPS signals comprising GPS data; receiving, via said onboard
vehicle subsystem, satellite radio system ("SRS") signals
originating from a satellite radio broadcast center, said SRS
signals comprising GPS correction data; and generating current
vehicle position data in response to said GPS data and said GPS
correction data.
2. A method according to claim 1, wherein receiving SRS signals
comprises receiving SRS signals transmitted from at least one SRS
terrestrial repeater.
3. A method according to claim 1, wherein receiving SRS signals
comprises receiving SRS signals transmitted from at least one SRS
satellite.
4. A method according to claim 1, wherein generating current
vehicle position data comprises adjusting said GPS data in
accordance with said GPS correction data.
5. A method according to claim 1, said GPS correction data
comprising differential GPS data.
6. A method according to claim 5, said differential GPS data
comprising Wide Area Augmentation System ("WAAS") data.
7. A method according to claim 1, said SRS signals further
comprising satellite radio data.
8. A method according to claim 1, further comprising separating
said GPS correction data from said SRS signals.
9. An onboard vehicle positioning system comprising: a global
positioning system ("GPS") receiver configured to receive GPS
signals originating from GPS satellites, said GPS signals
comprising GPS data; a satellite radio system ("SRS") receiver
configured to receive SRS signals originating from a satellite
radio broadcast center, said SRS signals comprising GPS correction
data; and processing logic coupled to said GPS receiver and to said
SRS receiver, said processing logic being configured to generate
current vehicle position data in response to said GPS data and said
GPS correction data.
10. A system according to claim 9, said GPS receiver and said SRS
receiver being combined into an integrated receiver assembly.
11. A system according to claim 9, said processing logic being
configured to generate said current vehicle position data by
adjusting said GPS data in accordance with said GPS correction
data.
12. A system according to claim 9, said GPS correction data
comprising differential GPS data.
13. A system according to claim 12, said differential GPS data
comprising Wide Area Augmentation System ("WAAS") data.
14. A system according to claim 9, said SRS signals further
comprising satellite radio data, and said SRS receiver being
configured to process said satellite radio data.
15. A system according to claim 14, further comprising data
extraction processing logic coupled to said SRS receiver, said data
extraction processing logic being configured to separate said GPS
correction data from said satellite radio data.
16. A method for providing positioning information to vehicles
supported by a vehicle positioning system, said method comprising:
obtaining global positioning system ("GPS") correction data for a
satellite radio system ("SRS") uplink station; uplink transmitting
said GPS correction data from said SRS uplink station to at least
one SRS satellite; and downlink transmitting SRS signals from said
at least one SRS satellite, said SRS signals comprising said GPS
correction data.
17. A method according to claim 16, further comprising: receiving,
by at least one SRS terrestrial repeater, a downlink SRS signal
containing GPS correction data; and retransmitting, by said at
least one SRS terrestrial repeater, said downlink SRS signal.
18. A method according to claim 16, said GPS correction data
comprising differential GPS data.
19. A method according to claim 18, said differential GPS data
comprising Wide Area Augmentation System ("WAAS").
20. A method according to claim 18, said SRS signals further
comprising satellite radio data.
Description
TECHNICAL FIELD
[0001] The present invention generally relates to vehicle
telematics systems. More particularly, the present invention
relates to a vehicle positioning system that utilizes global
positioning system ("GPS") and satellite radio system ("SRS")
data.
BACKGROUND
[0002] The prior art is replete with GPS systems and vehicle
positioning systems that leverage GPS data. An onboard telematics
system that utilizes non-survey grade GPS technology has practical
limitations on position availability and accuracy. One example
limitation is known as the "urban canyon" problem, which arises
when a GPS-enabled vehicle is located in close proximity to tall
buildings or other structures. A high level of multipath signals
occurs in such an environment due to the reflection of the GPS
satellite signals from the structures. In addition, some structures
may cause partial or total blockage of the GPS satellite signals.
Such blockage can be problematic because a GPS receiver must
receive GPS signals from at least three different GPS satellites to
obtain a position reading.
[0003] To improve location determination, some vehicle positioning
systems rely on dead reckoning ("DR") techniques. DR techniques
combine the GPS satellite measurements with additional sources of
location information, which may be onboard the vehicle. For
example, DR techniques may utilize inertial gyroscopes,
accelerometers, compass information, and wheel speed sensors. The
prior art contains a number of GPS/DR systems, including GPS/DR
systems utilized in vehicle applications. Unfortunately, the use of
DR technology in an onboard vehicle application may result in
additional cost and complexity to the system.
[0004] Military grade GPS systems utilize additional GPS data,
e.g., differential GPS data or Wide Area Augmentation System
("WAAS") data, to improve location determination. The use of
differential GPS data and WAAS data reduces known GPS error
sources, such as: ionosphere; clock; ephemeris; multipath;
troposphere; and receiver errors. Differential GPS data and WAAS
data, however, is not readily available for low-cost consumer
applications.
[0005] Accordingly, it is desirable to have a GPS-based vehicle
positioning system which minimizes the need to rely on DR
techniques to obtain an accurate position determination. In
addition, it is desirable to have a GPS-based vehicle positioning
system that operates reliably and accurately in an urban canyon
environment. Furthermore, other desirable features and
characteristics of the present invention will become apparent from
the subsequent detailed description and the appended claims, taken
in conjunction with the accompanying drawings and the foregoing
technical field and background.
BRIEF SUMMARY
[0006] An onboard vehicle positioning system according to the
invention is able to accurately determine the current position of
the vehicle using GPS data and GPS correction data transmitted via
one or more components of a satellite radio system ("SRS"). The
vehicle positioning system is able to generate accurate vehicle
position data while minimizing the need to rely on DR technology.
In accordance with one practical embodiment of the invention, the
vehicle positioning system leverages terrestrial repeaters of the
SRS, which enhances reliability in urban canyon environments.
[0007] The above and other aspects of the invention may be carried
out in one form by an onboard vehicle positioning system having a
GPS receiver configured to receive GPS signals originating from GPS
satellites, where the GPS signals comprise GPS data, an SRS
receiver configured to receive SRS signals originating from a
satellite radio broadcast center, where the SRS signals comprise
GPS correction data, and processing logic coupled to the GPS
receiver and to the SRS receiver. The processing logic is
configured to generate current vehicle position data in response to
the GPS data and the GPS correction data.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The present invention will hereinafter be described in
conjunction with the following drawing figures, wherein like
numerals denote like elements, and
[0009] FIG. 1 is a schematic representation of a satellite-based
vehicle positioning system according to an example embodiment of
the invention;
[0010] FIG. 2 is a schematic representation of an onboard vehicle
positioning system according to an example embodiment of the
invention;
[0011] FIG. 3 is a flow diagram of a GPS correction data
communication process according to an example embodiment of the
invention; and
[0012] FIG. 4 is a flow diagram of a vehicle positioning process
according to an example embodiment of the invention.
DETAILED DESCRIPTION
[0013] The following detailed description is merely exemplary in
nature and is not intended to limit the invention or the
application and uses of the invention. Furthermore, there is no
intention to be bound by any expressed or implied theory presented
in the preceding technical field, background, brief summary or the
following detailed description.
[0014] The invention may be described herein in terms of functional
and/or logical block components and various processing steps. It
should be appreciated that such block components may be realized by
any number of hardware, software, and/or firmware components
configured to perform the specified functions. For example, an
embodiment of the invention may employ various integrated circuit
components, e.g., memory elements, digital signal processing
elements, logic elements, look-up tables, or the like, which may
carry out a variety of functions under the control of one or more
microprocessors or other control devices. In addition, those
skilled in the art will appreciate that the present invention may
be practiced in conjunction with any number of practical vehicle
computer system platforms, architectures, and deployments, any
number of practical satellite positioning system platforms,
architectures, and deployments, and any number of practical
satellite radio system platforms, architectures, and deployments,
and that the particular system described herein is merely one
exemplary application for the invention.
[0015] For the sake of brevity, conventional techniques related to
vehicle computer modules, vehicle positioning data processing, GPS
data and system components, SRS data and system components, digital
data communication, and other functional aspects of the systems
(and the individual operating components of the systems) may not be
described in detail herein. Furthermore, the connecting lines shown
in the various figures contained herein are intended to represent
example functional relationships and/or physical couplings between
the various elements. It should be noted that many alternative or
additional functional relationships or physical connections may be
present in a practical embodiment.
[0016] The following description may refer to components or
features being "connected" or "coupled" together. As used herein,
unless expressly stated otherwise, "connected" means that one
component/feature is directly or indirectly connected to another
component/feature, and not necessarily mechanically. Likewise,
unless expressly stated otherwise, "coupled" means that one
component/feature is directly or indirectly coupled to another
component/feature, and not necessarily mechanically. Thus, although
the schematic block diagrams depict example arrangements of
elements, additional intervening elements, devices, features, or
components may be present in an actual embodiment (assuming that
the functionality of the systems or subsystems are not adversely
affected).
[0017] In FIGS. 1 and 2, the various system components may be
implemented with physical hardware elements, virtual machines,
and/or logical elements. Such system components may utilize general
purpose microprocessors, controllers, or microcontrollers that are
suitably configured to control the operation of the system
described herein, or at least govern the processes described
herein. In accordance with the practices of persons skilled in the
art of computer programming, the present invention is described
herein with reference to symbolic representations of operations
that may be performed by various processing or logical components.
Such operations are sometimes referred to as being
computer-executed, computerized, software-implemented, or
computer-implemented. It will be appreciated that operations that
are symbolically represented include the manipulation by the
various microprocessor devices of electrical signals representing
data bits at memory locations in the system memory, as well as
other processing of signals. The memory locations where data bits
are maintained are physical locations that have particular
electrical, magnetic, optical, or organic properties corresponding
to the data bits.
[0018] When implemented in software, various elements of the
present invention are essentially the code segments or instructions
that perform the various tasks. The program or code segments can be
stored in a processor-readable medium or transmitted by a computer
data signal embodied in a carrier wave over a transmission medium
or communication path. The "processor-readable medium" or
"machine-readable medium" may include any medium that can store or
transfer information. Examples of the processor-readable medium
include an electronic circuit, a semiconductor memory device, a
ROM, a flash memory, an erasable ROM (EROM), a floppy diskette, a
CD-ROM, an optical disk, a hard disk, a fiber optic medium, a radio
frequency (RF) link, or the like. The computer data signal may
include any signal that can propagate over a transmission medium
such as electronic network channels, optical fibers, air,
electromagnetic paths, or RF links. The code segments may be
downloaded via computer networks such as the Internet, an intranet,
a LAN, or the like.
[0019] FIG. 1 is a schematic representation of a vehicle
positioning system 100 configured in accordance with an example
embodiment of the invention. System 100 generally includes a
plurality of GPS satellites 102, one or more SRS satellites
104/106, one or more SRS uplink stations 108/110, one or more
terrestrial repeaters 112/114, an SRS broadcast center 116, a GPS
correction data source 118, and a vehicle 120 having an onboard
telematics system that includes at least an onboard vehicle
positioning subsystem. In a practical deployment, the telematics
system may also include telephony, data delivery, navigation,
vehicle status monitoring, and media features.
[0020] GPS satellites 102 represent satellites that continuously
broadcast their position for reception by ground-based GPS receiver
components. GPS signals originating at GPS satellites 102 include
GPS data indicative of the position of GPS satellites 102. There
are currently 24 GPS satellites 102 deployed in orbit; these 24 GPS
satellites need not be modified to support vehicle positioning
system 100. In practice, each GPS satellite 102 orbits the Earth in
a non-geostationary manner. The manner in which GPS satellites 102
communicate with ground-based components is known to those skilled
in the art of satellite communications and, therefore, will not be
described in detail herein.
[0021] SRS satellites 104/106 represent satellites that are
deployed in connection with services offered by an SRS provider.
One such provider offers commercial SRS services under the name XM
Satellite Radio Inc. The commercial SRS system maintained by this
provider utilizes two geostationary SRS satellites 104/106 combined
with a plurality of terrestrial repeaters 112/114 to broadcast SRS
signals to subscribers having a compatible SRS receiver, including
onboard vehicle SRS receivers. As described in more detail below,
the SRS signals may include GPS correction data combined with the
conventional SRS radio data. The manner in which SRS satellites
104/106 communicate with ground-based components is known to those
skilled in the art of satellite communications and, therefore, will
not be described in detail herein.
[0022] SRS broadcast center 116 may be a ground-based center that
provides SRS content to other components of the SRS system. It
should be appreciated that, although depicted as a distinct block
in FIG. 1, SRS broadcast center 116 may be incorporated into one or
more of SRS uplink stations 108/110. SRS broadcast center 116 may
provide SRS signals to SRS uplink stations 108/110 via suitable
data communication links 122/124 (which may include any number of
wired and/or wireless sections). In turn, SRS uplink stations
108/110 transmit SRS signals to SRS satellites 104/106 via suitable
uplink data communication links 126/128. Thereafter, SRS satellites
104/106 transmit SRS signals to ground-based receiver components
for local processing. In this regard, SRS satellites 104/106 may
transmit direct SRS signals 130/132 to vehicle 120, and/or indirect
SRS signals 134/136 to vehicle 120 via terrestrial repeaters
112/114.
[0023] A terrestrial repeater, as the name suggests, is a
ground-based component that serves as a relay station for SRS
signals. Generally, a terrestrial repeater receives an SRS signal
and amplifies it for retransmission at a higher transmit power. A
terrestrial repeater may also perform filtering, error correction,
or other conditioning of the SRS signal prior to retransmission.
Thus, terrestrial repeaters 112/114 enable relatively high power
SRS signals to reach vehicle 120 in environments where relatively
low power GPS signals from GPS satellites 102 are blocked. Although
not shown in FIG. 1, vehicle positioning system 100 may also
include intermediate terrestrial repeaters that receive SRS signals
from another terrestrial repeater. In this regard, an intermediate
terrestrial repeater may relay the SRS signals to another
intermediate terrestrial repeater and/or to vehicle 120.
Conventional terrestrial repeaters that are currently deployed to
support standard SRS systems can be utilized in system 100 without
modification.
[0024] In accordance with the example embodiment of the invention,
SRS signals include GPS correction data. As used herein, "GPS
correction data" means any data or information other than the
primary GPS data that originates from GPS satellites 102, where
such data or information supplements the primary GPS data. For
example, GPS correction data may include differential GPS data,
such as WAAS data. GPS correction data source 118 represents the
processing logic, entity, component, subsystem, file, device, or
other element that provides the GPS correction data to SRS
broadcast center 116. Although depicted as a distinct block in FIG.
1, GPS correction data source 118 may be incorporated into SRS
broadcast center 116.
[0025] In practice, the SRS signals also include the conventional
SRS radio data. In other words, the SRS signals contain GPS
correction data and SRS radio data. The two data types may be
transmitted using any suitable data communication technique or
protocol that facilitates data separation or extraction by the
receiving component.
[0026] In a practical deployment, vehicle positioning system 100
may include any number of GPS satellites 102, any number of SRS
satellites 104/106, any number of terrestrial repeaters 112/114,
and any number of SRS uplink stations 108/110. In addition, system
100 may include more than one SRS broadcast center 116, e.g., one
servicing each SRS satellite 104/106. System 100 as depicted in
FIG. 1 is merely one simple example used for ease of
description.
[0027] FIG. 2 is a schematic representation of an onboard vehicle
positioning system 200 configured in accordance with an example
embodiment of the invention. System 200 may, for example, be
deployed in vehicle 120 shown in FIG. 1. System 200 generally
includes a GPS receiver 202, an SRS receiver 204, vehicle position
processing logic 206 coupled to GPS receiver 202, and data
extraction processing logic 208 coupled to SRS receiver 204 and to
vehicle position processing logic 206. System 200 may also include
a GPS antenna 210 coupled to GPS receiver 202, where GPS antenna
210 is suitably configured to receive GPS signals, and an SRS
antenna 212 coupled to SRS receiver 204, where SRS antenna 212 is
suitably configured to receive SRS signals. In the example
embodiment, system 200 is configured to generate vehicle position
data 214 indicative of the current location of the vehicle, and SRS
radio data 216 that represents audio and/or video content suitable
for playback by the vehicle audiovisual system. In practice, system
200 may be incorporated into an onboard vehicle telematics system,
and the elements of system 200 may be realized with any number of
physical components. Indeed, GPS receiver 202, SRS receiver 204,
vehicle position processing logic 206, and data extraction
processing logic 208 may be realized as hardware, software, and/or
firmware in a single physical component. For example, GPS receiver
202 and SRS receiver 204 may be combined into an integrated
receiver assembly. Furthermore, although FIG. 2 depicts two
separate antenna components, GPS antenna 210 and SRS antenna 212
may be realized as a single antenna arrangement in a practical
embodiment.
[0028] GPS receiver 202 is suitably configured to receive, via GPS
antenna 210, GPS signals originating from GPS satellites. As
mentioned above, the GPS signals processed by GPS receiver 202
include GPS data. This GPS data may be considered as the "primary"
or "baseline" GPS data from which system 200 derives the current
location of the vehicle. The GPS data may be passed to vehicle
position processing logic 206 for further processing as described
below. SRS receiver 204 is suitably configured to receive, via SRS
antenna 212, SRS signals originating from an SRS broadcast center
(such as SRS broadcast center 116). Depending upon the particular
system architecture, the location of the vehicle, and other
practical considerations, SRS signals received by SRS receiver 204
may be transmitted by SRS satellites 104/106, terrestrial repeaters
112/114, or other components or subsystems of system 100. As
mentioned above, the SRS signals processed by SRS receiver 204
include GPS correction data (and possibly SRS radio data).
[0029] Data extraction processing logic 208 is suitably configured
to separate or extract the GPS correction data from the received
SRS signals. In this regard, data extraction processing logic 208
may perform any number of data communication techniques to isolate
the GPS correction data. The GPS correction data (identified by
reference number 218) may be passed to vehicle position processing
logic 206 to enable adjustment and/or correction of the primary GPS
data. In one practical embodiment, vehicle position processing
logic 206 adjusts/corrects the GPS data in accordance with the GPS
correction data to generate the current vehicle position data 214.
The specific manner in which vehicle position processing logic 206
adjusts the primary GPS data may vary from one system to
another.
[0030] FIG. 3 is a flow diagram of a GPS correction data
communication process 300 according to an example embodiment of the
invention. Process 300 is generally directed to the handling of GPS
correction data by an SRS provider. It should be appreciated that
the various tasks performed in connection with process 300 may be
performed by software, hardware, firmware, or any combination
thereof. For illustrative purposes, the following description of
process 300 may refer to elements mentioned above in connection
with FIG. 1. In practical embodiments, portions of process 300 may
be performed by different elements of the described system,
including, without limitation, the SRS broadcast center, the SRS
uplink stations, or the terrestrial repeaters. It should also be
appreciated that process 300 may include any number of additional
or alternative tasks, the tasks shown in FIG. 3 need not be
performed in the illustrated order, and process 300 may be
incorporated into a more comprehensive procedure or process having
additional functionality not described in detail herein.
[0031] GPS correction data communication process 300 begins by
obtaining GPS correction data for an SRS uplink station (task 302).
As described above, the GPS correction data may be differential GPS
data, such as WAAS data, obtained from any available source. In
practice, the GPS correction data is provided to an SRS broadcast
center for processing along with the normal SRS radio data.
Ultimately, the GPS correction data is sent to the SRS uplink
station, which then uplink transmits the GPS correction data to one
or more SRS satellites (task 304). In a practical embodiment, the
GPS correction data may be combined with (or included with) SRS
radio data in suitably formatted SRS signals. The SRS uplink
station may transmit the SRS signals and/or the GPS correction data
to the SRS satellites using techniques and protocols known to those
skilled in satellite data communications.
[0032] The SRS satellites perform downlink transmission of SRS
signals (task 306), where the SRS signals comprise the GPS
correction data. The SRS satellites may transmit the SRS signals
and/or the GPS correction data using techniques and protocols known
to those skilled in satellite data communications. Indeed, the SRS
satellites need not be modified to support GPS correction data
communication process 300. As mentioned above, some SRS signals may
be directly transmitted from an SRS satellite to the receiving
vehicle, while other SRS signals may be indirectly transmitted to
the receiving vehicle via one or more terrestrial repeaters.
[0033] If a terrestrial repeater is included in the data
transmission path, then downlink SRS signals comprising GPS
correction data are received by the terrestrial repeater (task
308). The terrestrial repeater may perform conditioning or
processing of the received SRS signal before retransmitting the
downlink SRS signal (task 310). As described above, such
retransmission may be directed to another terrestrial repeater
and/or to the receiving vehicle. Notably, the transmission of SRS
signals occurs in a broadcast manner and without any specific
receiving vehicle or component as a destination.
[0034] FIG. 4 is a flow diagram of a vehicle positioning process
400 according to an example embodiment of the invention. Process
400 is generally directed to the handling of satellite-based
positioning data by an onboard vehicle telematics system, e.g., a
vehicle positioning system as described above. It should be
appreciated that the various tasks performed in connection with
process 400 may be performed by software, hardware, firmware, or
any combination thereof. For illustrative purposes, the following
description of process 400 may refer to elements mentioned above in
connection with FIG. 2. In practical embodiments, portions of
process 400 may be performed by different elements of the described
system, including, without limitation, GPS receiver 202, SRS
receiver 204, vehicle position processing logic 206, or data
extraction processing logic 208. It should also be appreciated that
process 400 may include any number of additional or alternative
tasks, the tasks shown in FIG. 4 need not be performed in the
illustrated order, and process 400 may be incorporated into a more
comprehensive procedure or process having additional functionality
not described in detail herein.
[0035] Vehicle positioning process 400 may begin by receiving, via
the onboard vehicle subsystem, GPS signals originating from GPS
satellites (task 402). The GPS signals comprise GPS data, as
explained above. In addition, the onboard vehicle subsystem also
receives SRS signals originating from an SRS broadcast center. The
SRS signals comprise GPS correction data and SRS radio data, as
explained above. In practice, the onboard vehicle subsystem may
receive direct SRS signals transmitted from SRS satellites (task
404) and/or retransmitted SRS signals transmitted from terrestrial
repeaters (task 406).
[0036] The onboard vehicle subsystem may process the received SRS
signals to separate or extract the GPS correction data from the SRS
signals (task 408) and/or to separate or extract the SRS radio data
from the SRS signals. The SRS radio data can then be processed in a
conventional manner to facilitate playback by the vehicle
audiovisual system. The extracted GPS correction data may then be
utilized to adjust or correct the primary GPS data (task 410) using
suitable correction techniques. In other words, the primary GPS
data received during task 402 is adjusted in accordance with the
GPS correction data. In addition, the onboard vehicle subsystem
generates current vehicle position data based on the corrected GPS
data (task 412). In this regard, the current vehicle position data
is generated in response to the primary GPS data and in response to
the GPS correction data.
[0037] The onboard vehicle subsystem may employ post-processing or
real-time timing methods to synchronize the GPS correction data
with the primary GPS data. Briefly, one possible post-processing
technique is performed as follows: (1) the SRS uplink station
calculates range corrections and time tags its uplink
transmissions; (2) the onboard vehicle subsystem time tags the
currently measured ranges to the SRS satellites; and (3) at a
defined later point in time, both the SRS uplink station and the
onboard vehicle subsystem can download their respective time tagged
information to onboard telematics systems for use in connection
with enhanced vehicle positioning.
[0038] For precise navigation applications, the real-time technique
is preferred to eliminate time delays that may be associated with
the post-processing technique. One possible example of real-time
processing begins with the SRS uplink station periodically (e.g.,
every second) sending the GPS correction data to the onboard
vehicle subsystem. This may be accomplished via a direct
transmission to the vehicle or via the SRS satellites. Once the
onboard vehicle subsystem receives this information, it can be
processed with the real-time GPS data to provide the improved
location measurement for the vehicle.
[0039] In a practical embodiment of the invention, the current
vehicle position data may be further processed by the onboard
vehicle subsystem to facilitate rendering or display of the current
vehicle position in connection with, e.g., an onboard navigation
system. Alternatively (or additionally), the current vehicle
position data may be further processed by the onboard vehicle
subsystem to facilitate transmission to a monitoring service or to
facilitate onboard storage. As depicted by the arrow from task 412
to task 402, vehicle positioning process 400 may be a continuous
process that repeats itself to enable real-time updating of the
vehicle position.
[0040] In summary, an onboard vehicle positioning system according
to the invention leverages the reliable coverage range and
relatively high transmit power of an SRS system to provide enhanced
GPS-based location determination. The system is capable of
providing an enhanced location in an urban canyon environment where
conventional GPS satellite signal transmissions may be highly
reflected and/or completely blocked. Furthermore, the system
utilizes the SRS system to convey GPS correction data, such as
differential GPS data, that improves the accuracy of standard GPS
location readings.
[0041] While at least one exemplary embodiment has been presented
in the foregoing detailed description, it should be appreciated
that a vast number of variations exist. It should also be
appreciated that the exemplary embodiment or exemplary embodiments
are only examples, and are not intended to limit the scope,
applicability, or configuration of the invention in any way.
Rather, the foregoing detailed description will provide those
skilled in the art with a convenient road map for implementing the
exemplary embodiment or exemplary embodiments. It should be
understood that various changes can be made in the function and
arrangement of elements without departing from the scope of the
invention as set forth in the appended claims and the legal
equivalents thereof.
* * * * *